Polyone Corp. Reveals FDA Compliant Nanocomposite Plastics for Food Contact

Polyone Corporation David A. Jarus and Guoqiang Qian have developed nanocomposite plastics that can be used in contact with food and are compliant with U.S. Food and Drug regulations. United States Patent Application 20090292055 details nanocomposites that are made from melt-mixing of polyethylene with organoclay in the presence of a maleated polypropylene. Unexpectedly, the maleated polypropylene and polyethylene are sufficiently compatible to permit excellent dispersion of the organoclay in the nanocomposite. Because maleated polypropylene is compliant with U.S. Food and Drug Administration regulations, though maleated polyethylene is not, one can use resulting nanocomposites for articles to be in contact with human food.

PolyOne Corporation provides specialized polymer materials with operations in thermoplastic compounds, specialty polymer formulations, color and additive systems, thermoplastic resin distribution, and specialty polyvinyl chloride (PVC) resins

The mixture of organoclays and polyolefins, commonly called nano-olefins, is highly desired because the organoclays can contribute stiffness and toughness properties to polyolefins for extruded or molded articles. Polyolefins for molded or extruded articles have been useful since the mid-20th Century. Organoclays, smectite inorganic clays intercalated with organic ions, such as quaternary ammonium, have become useful in the last decade. Organoclays are expensive additives for polyolefins such as polypropylene (PP).

When used packaging, particularly food packaging such as films, each of the ingredients need to be listed in the USA Title 21 of the Code of Federal Regulations, which is regulated by the United States Food and Drug Administration (FDA).

Polyone’s polyethylene nanocomposite is FDA compliant. "FDA compliant" means that each of the ingredients of the polyolefin nanocomposites of the invention are listed in 21 CFR as generally regarded as safe ("GRAS") for food contact applications.

Polyone solved the dispersion problem by using a polypropylene-based compatibilizer with a mixture of organoclay and a polyethylene resin matrix. More particularly, the polypropylene-based compatibilizer is a maleated polypropylene. Unexpectedly, it was found that even though a maleated polypropylene ("PP-g-MAH") is considered to be immiscible with polyethylene ("PE"), the PP-g-MAH provides acceptable compatibility for dispersing the organoclay into the PE matrix. The unexpected compatibility (in spite of apparent immiscibility) of PP-g-MAH with PE means that a nanoconcentrate (highly concentrated organoclay in thermoplastic matrix) can be blended with adequate organoclay dispersion and with FDA compliant ingredients. Nanocomposites also offer flame-retardancy properties because such nanocomposite formulations burn at a noticeably reduced burning rate and a hard char forms on the surface. They also exhibit minimum. dripping and fire sparkling.

Organoclay is obtained from inorganic clay from the smectite family. Smectites have a unique morphology, featuring one dimension in the nanometer range. Montmorillonite clay is the most common member of the smectite clay family. The montmorillonite clay particle is often called a platelet, meaning a sheet-like structure where the dimensions in two directions far exceed the particle's thickness.

The nanocomposite can serve either as a concentrate or as a compound. If the former, then the nanocomposite is an intermediate product, an ingredient to be added with other ingredients to subsequent compounding steps in a batch or continuous mixing apparatus. The dilution or "let-down" of the concentrate into the compound can result in an organoclay concentration in the compound ranging from about 4 to less than 15 weight percent, and preferably from about 6 to about 12 weight percent, to maximize stiffness and toughness performance properties with minimal concentration of organoclay in the nanocomposite. Ultimately, the compound is formed into an article or film using a subsequent extrusion or molding techniques

US Technology Corp's Nanoclay Blast Media Faster, Cheaper, Gentler and More Durable

US Technology Corporation (Canton, OH) provides comprehensive surface preparation and coatings removal to the aerospace, aircraft, electronics, automotive, shipping, petroleum and structural industries. Raymond F. Williams and Daniel L. Kinsinger detail a method for making  polymeric blast media products with nanoclays in U.S. Patent 7,622,518. The first step involves blending a melamine compound with a cellulosic material and compression molding the first blend. This first blend is then cooled and then ground. In the next step of this method, a urea compound is blended with a nano-clay material to produce a second blend and compression molded. This compression molded second blend is then ground to produce a particulate second blend. The particulate first blend is then blended with the particulate second blend to yield a blast media product. It can cost effectively removes organic coatings from substrates without substantial risk of damage to sensitive metal or composite substrates according to inventors Williams and Kinsinger.

The blast media with nanoclay may be used for removal of standard aerospace coatings such as epoxy primers and polyurethane topcoats from very sensitive metal or composite substrates with better efficiency than was previously available. This media coating can be removed at accelerated speeds as compared to prior art blast media. The safety factor of this media on thin skin aluminum or composite surfaces is high. Coatings can be removed with virtually no damage to such substrates, leaving protective coatings such as cladding and anodizing intact. Also, the durability of this media helps to maintain economic feasibility in large-scale aerospace applications.

Various different embodiments of this media address specific applications related to the aerospace industry and industry in general. All of these embodiments make use of nanometer-sized montmorillonite clay particles, which improve surface integrity and provide advantages in the mechanical and thermal properties of the polymer. These results are achieved with no increase in specific gravity due to the very low amounts of nano-particle needed, i.e. between 1/2% and 5% by weight. These results demonstrate that the overall increase in efficiency of this media is three to four times faster than unfilled polymer while the durability has more than doubled.

The patent also encompasses an abrasive media for the removal of coating or for the preparation of surfaces prior to coating or cleaning comprising a thermosetting polymer with an additive, wherein the additive has a major dimension and a minor dimension. The minor dimension is from about 1 nm to about 20 nm. The additive may be the nano-clay material, or alternatively may be a polyhedral oligomeric silsesquioxane material.

The patent also encompasses a method of making a sanding pad for removing an organic coating from a substrate comprising the steps of blending a liquid polymeric material with a nano-clay material to produce a first blend, blending a cellulosic material with said first blend to produce a second blend. This second blend is then extruded to form a continuous sheet of abrasive material into individual pads.

Figure 1 shows a brief flow chart of the manufacturing process for nanoclay blast media.

MSU Researchers Create Improved Nanocomposite Biodegradeable Film for Packaging

“Green” biobased polymer-clay nanocomposite packaging technologies with improved oxygen and moisture barrier properties have been developed by Michigan State University (MSU) (East Lansing, MI) researchers. Amar K. Mohanty, Yashodhan Parulekar, Mariappan Chidambarakumar, Napawan Kositruangchai and Bruce R. Harte created biodegradable polymeric nanocomposite compositions that are particularly useful for food packaging. The compositions are comprised of three materials: a biobased biodegradable polymer of polylactic acid (PLA) or polyhydroxybutyrate (PHB), a petroleum-based biodegradable polymer (poly-(butylene adipate-co-terephthalate) (PBAT), and a fatty acid triglyceride quaternary ammonium salt modified nanoclay which together yield a high-barrier, biodegradable material for packaging. The composition is formed by reactive blending, particularly extrusion, according to U.S. Patent 7,619,025.

Blending a biobased biodegradable polymer and a petroleum-based biodegradable polymer creates a material with high bio-content to satisfy environmental and sustainability issues. High/good barriers are achieved by adding a nanoclay, but improvements are only achieved if optimum dispersion and compatibility are created. Clay is inherently hydrophilic and hence does not mix with the organic polymer matrix. This leads to agglomeration and poor properties and this has to be overcome by specifically modifying the clay surface. Performance limitations and high cost however, have limited these biopolymers and biodegradable polymers to niche markets. Nano-reinforcements of such materials with specific organoclays create new value-added applications and lead to more usage, which will subsequently reduce the cost.

The specific organic modified clays are synergistic to the enhancement of barrier properties. The multilayer plastic films currently used for gas and water vapor barrier purposes can thus be replaced by a monolayer of plastic nanocomposite film.

The total nano-enabled food and beverage packaging market in the year 2008 was $4.13 billion, which is expected to grow in 2009 to $4.21 billion and forecasted to grow to $7.30 billion by 2014, at a compound average growth rate (CAGR) of 11.65%. Active technology represents the largest share of the market, with $2.7 billion in 2008, followed by intelligent packaging with $1.03 billion, and finally, controlled release packaging of $360 million. In 2014, the active segment will remain the largest, with $4.35 billion in sales, and the intelligent segment will grow to $2.47 billion sales, according to Nano-Enabled Packaging For The Food And Beverage Industry – A Global Technology, Industry And Market Analysis published by Innovative Research and Products Inc (iRAP, Inc)

Roofing Materials Made with Asphalt Nanocomposites

Building Materials Investment Corporation (Wilmington, DE), a part of GAF Materials Corporation the largest U.S. roofing materials manufacturer, has patented an asphalt nanocomposite materials that can be used in roofing shingles and other building materials The asphalt-based nanocomposites are particle-filled matrices that include an asphalt flux or derivate and a layered clay mineral in an amount ranging from about 1% to 15% of weight. The nanocomposites result in improved mechanical properties such as heat deflection temperature, increased stiffness, higher tensile strength and better fire retardancy.

The asphalt-based nanocomposite is a nano-dispersion that is characterized as having higher melt viscosity as well as new crystallographic order evidenced in wide-angle X-ray diffraction (WAXD) studies. Such nanocomposites have superior tensile strength and significantly higher Young's modulus relative to their respective raw or filled coatings without nanoclays. The asphalt-based nanocomposite can be used as a coating for any material layer of a roofing shingle, according to inventors Vinay Mehta, Brian Kanze, Krishna Srinivasan and Awdhoot Vasant Kerkar, writing in U.S. Patent 7,582,155. It is worth noting, that the term "asphalt-based nanocomposite" denotes a composite material comprising asphalt as the major component. This system is distinct from polymer-based nanocomposites, in which a polymer is the major component.

The asphalt-based nanocomposite is made of particle filled layered clay minerals dispersed into a matrix of asphalt. The asphalt molecules intercalate (or exfoliate) between the clay mineral layers. decrease in ultimate elongation was, however, anticipated since the addition of polymer-based nanocomposites to different systems in the prior art also shows a similar decrease in elongation. The decrease in ultimate elongation is a result of a stiffer product being formed when the nanocomposite is employed.

Layered clay materials such as, for example, montmorillonite, hectorite, saponite and the like, are composed of silicate layers that have a thickness of about 1 to a few nanometers. Dispersions of such layered clay materials in polymers are frequently referred to as polymer-based nanocomposites. These are the type of nanomaterials used in the asphalt nanocomposite.

The asphalt-based nanocomposite can be prepared using a variety of methods, including: (1) a direct blending method; (2) a method in which asphalt is first fractionated into its multiple (usually four) components and then a layered clay mineral is blended therein; (3) a method in which a layered clay mineral is added to an asphalt flux or derivative thereof prior to blowing (i.e., oxidizing); or (4) a method in which asphalt flux or its derivative is first solubilized in an organic solvent, then mixed with a layered clay mineral and thereafter evaporated to remove the organic solvent.

Ciba Specialty Reveals Process to Improve Polymers with Nanoclays

Ciba Specialty Chemicals Corporation (Tarrytown, NY) developed cationic alkoxyamines as polymerization initiators/regulators in a controlled stable free radical polymerization process to produce intercalated and/or exfoliated nanoparticles from natural or synthetic clays. The process results in improved nanocomposites and nanocomposite compositions for use in paints, inks, coatings, sealants, caulks, adhesives, reactive diluents and as plastic additives for thermoplastic materials, according to U.S. Patent 7,595,359.

One way of improving polymer properties is by adding a natural or synthetic clay material to polymers to form composite materials. However, incorporating clays into polymers may not provide a desirable improvement in the physical properties, particularly mechanical and optical properties of the polymer may be adversely affected. Nanocomposite compositions containing finely dispersed natural or synthetic clay with at least partially intercalated and/or exfoliated layers and mixtures of ethylenically unsaturated monomers and/or polymers have attracted much interest in recent years. According to Ciba inventors Andreas Muhlebach, Peter Nesvadba and Andreas Kramer, nanoclay materials combine the desired effects of dispersed clay bu avoid the negative influence on the mechanical or optical properties. The nanocomposite compositions can be optically almost transparent, indicating the fine distribution, on the nanometer scale, of the clay.

Ciba provides alkoxyamines, which can be anchored to natural or synthetic clays by a cationic anchor group and which have a high reactivity towards acrylates, methacrylates, styrene and other monomers resulting in a controlled molecular weight with narrow molecular weight distribution. With these compounds polymerization leads to high monomer to polymer conversions in short times and at relatively low temperatures. In contrast to conventional radical polymerization, controlled radical polymerization permits the adjustment of the molecular weight of all growing chains almost uniformly to a predetermined length (low polydispersity), resulting in an almost ideal dispersion of the intercalated and/or exfoliated clay particles.